Electricity systems are very complex systems and are composed of numerous transmission lines, generators and loads. The generating stations are generally far away from load centres and that may cause transmission line congestion and overloading. Series capacitive compensation is the most economical way to increase transmission capacity and improve transient stability of transmission grids. However, one of the impeding factors for the widespread use of series capacitive compensation is the potential risk of Subsynchronous Resonance (SSR). Subsynchronous Resonance is a phenomenon in which electrical power is exchanged with the generator shaft system in an increasing manner which may result in damage to the turbine generator shaft system. Therefore, mitigating SSR continues to be a subject of research and development aiming at developing effective SSR countermeasures.<p>This research work presents new methods of alleviating the SSR problem using a Static Synchronous Series Compensator (SSSC) and a Static Synchronous Compensator (STATCOM). These methods are based on using the SSSC and STATCOM to inject unbalanced series quadrature voltages and unbalanced shunt reactive currents in transmission line just after clearing faults. When the subsynchronous oscillations drive unsymmetrical phase currents, the developed electromagnetic torque will be lower than the condition when the three-phase currents are symmetrical. The unsymmetrical currents result in a lower coupling strength between the mechanical and the electrical system at asynchronous oscillations. Therefore, the energy exchange between the electrical and the mechanical systems at subsynchronous oscillations will be suppressed, thus, avoiding the build-up of torsional stresses on the generator shaft systems under subsynchronous resonance condition. The validity of proposed methods are demonstrated by time simulation results using the electromagnetic transient program EMTP-RV.

The thesis reports the results of comprehensive studies carried out to explore the impact of midpoint FACTS Controllers (STATCOM and SVC) on the generator distance phase backup protection in order to identify important issues that protection engineers need to consider when designing and setting a generator protection system. In addition, practical, feasible and simple solutions to mitigate the adverse impact of midpoint FACTS Controllers on the generator distance phase backup protection are explored. The results of these studies show that midpoint FACTS Controllers have an adverse effect on the generator distance phase backup protection. This adverse effect, which can be in the form of underreach, overreach or a time delay, varies according to the fault type, fault location and generator loading. Moreover, it has been found that the adverse effect of the midpoint FACTS Controllers extends to affect the coordination between the generator distance phase backup protection and the generator steady-state overexcited capability limit. The Support Vector Machines classification technique is proposed as a replacement for the existing generator distance phase backup protection relay in order to alleviate potential problems. It has been demonstrated that this technique is a very promising solution, as it is fast, reliable and has a high performance efficiency. This will result in enhancing the coordination between the generator phase backup protection and the generator steady-state overexcited capability limit in the presence of midpoint FACTS Controllers. The thesis also presents the results of investigations carried out to explore the impact of the generator distance phase backup protection relay on the generator overexcitation thermal capability. The results of these investigations reveal that with the relay settings according to the current standards, the generator is over-protected and the generator distance phase backup protection relay restricts the generator overexcitation thermal capability during system disturbances. This restriction does not allow the supply of the maximum reactive power of the generating unit during such events. The restriction on the generator overexcitation thermal capability caused by the generator distance phase backup protection relay highlights the necessity to revise the relay settings. The proposed solution in this thesis is to reduce the generator distance phase backup protection relay reach in order to provide secure performance during system disturbances.

Electricity systems are very complex systems and are composed of numerous transmission lines, generators and loads. The generating stations are generally far away from load centres and that may cause transmission line congestion and overloading. Series capacitive compensation is the most economical way to increase transmission capacity and improve transient stability of transmission grids. However, one of the impeding factors for the widespread use of series capacitive compensation is the potential risk of Subsynchronous Resonance (SSR). Subsynchronous Resonance is a phenomenon in which electrical power is exchanged with the generator shaft system in an increasing manner which may result in damage to the turbine generator shaft system. Therefore, mitigating SSR continues to be a subject of research and development aiming at developing effective SSR countermeasures.<p>This research work presents new methods of alleviating the SSR problem using a Static Synchronous Series Compensator (SSSC) and a Static Synchronous Compensator (STATCOM). These methods are based on using the SSSC and STATCOM to inject unbalanced series quadrature voltages and unbalanced shunt reactive currents in transmission line just after clearing faults. When the subsynchronous oscillations drive unsymmetrical phase currents, the developed electromagnetic torque will be lower than the condition when the three-phase currents are symmetrical. The unsymmetrical currents result in a lower coupling strength between the mechanical and the electrical system at asynchronous oscillations. Therefore, the energy exchange between the electrical and the mechanical systems at subsynchronous oscillations will be suppressed, thus, avoiding the build-up of torsional stresses on the generator shaft systems under subsynchronous resonance condition. The validity of proposed methods are demonstrated by time simulation results using the electromagnetic transient program EMTP-RV.

The thesis reports the results of comprehensive studies carried out to explore the impact of midpoint FACTS Controllers (STATCOM and SVC) on the generator distance phase backup protection in order to identify important issues that protection engineers need to consider when designing and setting a generator protection system. In addition, practical, feasible and simple solutions to mitigate the adverse impact of midpoint FACTS Controllers on the generator distance phase backup protection are explored. The results of these studies show that midpoint FACTS Controllers have an adverse effect on the generator distance phase backup protection. This adverse effect, which can be in the form of underreach, overreach or a time delay, varies according to the fault type, fault location and generator loading. Moreover, it has been found that the adverse effect of the midpoint FACTS Controllers extends to affect the coordination between the generator distance phase backup protection and the generator steady-state overexcited capability limit. The Support Vector Machines classification technique is proposed as a replacement for the existing generator distance phase backup protection relay in order to alleviate potential problems. It has been demonstrated that this technique is a very promising solution, as it is fast, reliable and has a high performance efficiency. This will result in enhancing the coordination between the generator phase backup protection and the generator steady-state overexcited capability limit in the presence of midpoint FACTS Controllers. The thesis also presents the results of investigations carried out to explore the impact of the generator distance phase backup protection relay on the generator overexcitation thermal capability. The results of these investigations reveal that with the relay settings according to the current standards, the generator is over-protected and the generator distance phase backup protection relay restricts the generator overexcitation thermal capability during system disturbances. This restriction does not allow the supply of the maximum reactive power of the generating unit during such events. The restriction on the generator overexcitation thermal capability caused by the generator distance phase backup protection relay highlights the necessity to revise the relay settings. The proposed solution in this thesis is to reduce the generator distance phase backup protection relay reach in order to provide secure performance during system disturbances.

Orientador: Anésio dos Santos Júnior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-17T09:21:57Z (GMT). No. of bitstreams: 1 Tortelli_OdilonLuis_D.pdf: 1186857 bytes, checksum: 5e13f6473425287a72e7c516fe18dc39 (MD5) Previous issue date: 2010 / Resumo: Este trabalho apresenta um estudo relativo ao problema de alocação, operação e análise de desempenho de Controladores FACTS em Sistemas Elétricos de Potência. Nesse sentido são descritos os mais importantes Controladores FACTS em termos de suas características operativas e potencialidades e uma rotina computacional para cálculo de fluxo de potência, baseada no método de Newton-Raphson incluindo a representação dos diversos Controladores FACTS é apresentada. A abordagem de alocação e determinação ótima dos parâmetros de controle é vista de maneira desacoplada, sendo o problema de alocação tratado pela técnica de Algoritmos Genéticos e a otimização dos parâmetros dos controladores por meio do método do Gradiente Reduzido. É também proposta uma estratégia alternativa de alocação/operação baseada na funcionalidade dos diferentes controladores. Também neste trabalho, é apresentado o conceito de tracking de potência, que é estendido para permitir uma avaliação não convencional da interferência dos Controladores FACTS na redistribuição dos fluxos de potência. A fim de sumarizar os diversos aspectos associados a alocação, operação e análise de desempenho de Controladores FACTS, um estudo de caso é apresentado / Abstract: This thesis presents a study related to the problem of allocating, operating and analyzing the performance of FACTS Controllers in Electrical Power Systems. In this sense, the most important FACTS controllers are described in terms of their operational features and their potentialities and, also, a computational routine for calculating the power flow, based on the Newton-Raphson method and including the representation of several FACTS controllers, is developed. The allocation process and the optimal controllers adjustment are conducted in a decoupled approach based on expansion and operational planning aspects. Genetic Algorithms are employed in the allocation procedure and the controllers optimization is dealt by the classical Reduced Gradient technique. An alternative strategy for allocation/operation of the controllers is proposed, based on the functionality of the different FACTS devices. The concept of Power tracking is also presented and expanded in order to allow a non-conventional evaluation about the interference of the FACTS controllers in the redistribution of the power flows. To summarize the several aspects connected to the allocation, operation and performance of the FACTS controllers, a case study is presented / Doutorado / Energia Eletrica / Doutor em Engenharia Elétrica

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-26T19:40:40Z No. of bitstreams: 1 MarcosSilvaMontelo.pdf: 2980665 bytes, checksum: 3b07ab02be8c6a4e17cda1a61787ffe2 (MD5) / Made available in DSpace on 2017-06-26T19:40:40Z (GMT). No. of bitstreams: 1 MarcosSilvaMontelo.pdf: 2980665 bytes, checksum: 3b07ab02be8c6a4e17cda1a61787ffe2 (MD5) Previous issue date: 2016-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / In this work is investigated the performance of the GMRES Method in studies of power flow extremely loaded, ill-conditioned and including FACTS Controllers, focusing on Jacobian matrix with high numbers of conditioning and real eigenvalue close to zero, in order to consolidate the virtues of GMRES in ill-conditioned problems. From this information you can set operating scenarios that may indicate points of robustness and GMRES efficiency. Consolidating test systems (hypothetical and actual) of difficult convergence associated with extremely high loaded, is also part of research to create s cenarios close to reality, or that may occur in practice. The primary purpose of the inclusion of FACTS is to assess the impact that these devices can cause the Jacobian matrix. These characteristics are informed through eigenvalues and conditioning number. In addition, we propose an iterative solver developed in MATLAB platform for power flow studies and a detailed investigation of the influence of the reordering and the e limination of non-null elements in the quality of the preconditioner of incomplete factors. The proposed methodology was applied to hypothetical and real systems with FACTS controllers, and the results of the experiments showed the greater efficiency of the iterative solver GMRES in most simulations. It was found that the larger the size of the electrical system and the worse their numeric characteristics, the better its performance. / Neste Trabalho é investigado o desempenho do Método GMRES em estudos de Fluxo de potência extremamente carregados, mal condicionados e incluindo Controladores FACTS, enfocando matrizes Jacobianas com elevados números de condicionamento e autovalores reais próximos de zero, a fim de consolidar virtudes do GMRES na solução de problemas mal-condicionados. A apartir destas informações será possível estabelecer cenários de operação que poderão indicar pontos de robustez e eficiência do GMRES. A consolidação de sistemas-teste (hipotéticos e reais) de difícil convergência associados a carregamentos extremamente elevados, também faz parte das investigações para criar cenários próximos da realidade, ou seja, que possam ocorrer na prática. O objetivo primário da inclusão de FACTS está em avaliar o impacto que estes equipamentos podem causar na matriz Jacobiana. Estas características são informadas através de autovalores e número de condicionamento. Além disso, propõe-se um solucionador iterativo desenvolvido na plataforma MATLAB para estudos de fluxo de potência e uma investigação detalhada da influência do reordenamento e da eliminação de elementos não-nulos na qualidade do pré-condicionador de fatores incompletos. A metodologia proposta foi aplicada em sistemas hipotéticos e reais com Controladores FACTS, e os resultados dos experimentos mostraram a maior eficiência do solucionador iterativo GMRES em grande parte das simulações realizadas. Verificou-se que, quanto maior a dimensão do sistema elétrico e quanto pior suas características numéricas, melhor seu desempenho.

Made available in DSpace on 2016-08-17T14:52:56Z (GMT). No. of bitstreams: 1 Sergio Leon Escalante Cardenas.pdf: 1233424 bytes, checksum: 8be8a81742f69038e591f72b968c13ee (MD5) Previous issue date: 2005-02-28 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work presents the economical and technical aspects of FACTS (flexible ac transmission systems) controllers in steady-state operation of electric power systems (EPS). There Controllers are used in EPS to increase the power transfer limit in the transmission lines and to improve the electromechanical and voltage stability. The models considered in this research are: SVC, TCSC, STATCOM, SSSC and UPFC. The modeling of HVDC link including a commutation capacitor for converter (CCC) is also presented. A Newton-Raphson power flow computer program was implemented in order to assess the steady-state operation of FACTS Controllers. On the other hand, for economic assessment of FACTS application, an optimal power flow (OPF) based on interior point method was implemented and prospectively an OPF using genetic algorithms has been proposed. The studied FACTS Controllers were applied to the IEEE 30 bus and IEEE 118 bus test systems, and a configuration of a real power system regarding to the Brazilian National Interconnected System (SIN) represented with 2256 buses. The analysis of the results obtained from the tests indicates that the operation of a EPS with FACTS is more flexible and presents advantages, such as: lines power transfer increase, possibility of power flow reversal in the lines, a better voltage control in remote buses and operation costs lowering, keeping operation restrictions and fixing both, bus voltages and transmission line power flows. / Neste trabalho são apresentados os aspectos técnicos e econômicos da aplicação dos Controladores FACTS (flexible ac transmission systems) na operação dos sistemas de energia elétrica (SEE) em regime permanente. Os FACTS são utilizados nos SEE para aumentar o limite da transferência de potência nas linhas de transmissão e para melhorar a estabilidade eletromecânica e de tensão. Os modelos dos Controladores FACTS considerados nesta pesquisa são: SVC, TCSC, STATCOM, SSSC e UPFC. Uma modelagem do elo de corrente contínua ou HVDC, inclusive com capacitor de comutação de conversor (CCC) também é apresentada. Para avaliar os aspectos técnicos na operação em regime permanente dos FACTS foi implementado um programa computacional de fluxo de potência baseado no método Newton Raphson. Já para a avaliação econômica da aplicação dos Controladores FACTS foi implementado um fluxo de potência ótimo (FPO) com o método de pontos interiores e prospectivamente foi proposto um FPO adotando algoritmos genéticos. Os Controladores FACTS estudados foram aplicados aos sistemas de teste IEEE de 30 barras, IEEE de 118 barras e uma configuração de um sistema de potência real pertencente ao sistema interligado nacional (SIN) brasileiro representado com 2256 barras. A análise dos resultados obtidos nos testes indica que a operação de um SEE que possui FACTS é mais flexível com vantagens, tais como: aumento da transferência de potência nas linhas, possibilidade de inversão de fluxo de potência nas linhas, um melhor controle de tensão nos barramentos remotos e redução do custo de operação mantendo as restrições de operação impostas e fixando tanto as tensões em barras quanto os fluxos de potência nas linhas.

No description available.

The focus of this research is on deriving small signal stability models for different Flexible AC Transmission Systems devices by introducing a simple systematic method that is applicable to any dynamic device. Two different small signal models for Unified Power Flow Controllers are introduced. One model is called the power control mode and the other model is the voltage control mode. The two models are compared from transient stability point of view to show the necessity of developing both models for UPFC. The thesis also shows how to derive the small signal stability model of Static Synchronous Compensator, as the shunt branch of UPFC. The small signal stability models of both devices are then validated to ensure the accuracy of the derived models. STATCOM and UPFC power control mode are validated against PSCAD. The UPFC voltage control mode is validated against nonlinear solution of system equations.

The focus of this research is on deriving small signal stability models for different Flexible AC Transmission Systems devices by introducing a simple systematic method that is applicable to any dynamic device. Two different small signal models for Unified Power Flow Controllers are introduced. One model is called the power control mode and the other model is the voltage control mode. The two models are compared from transient stability point of view to show the necessity of developing both models for UPFC. The thesis also shows how to derive the small signal stability model of Static Synchronous Compensator, as the shunt branch of UPFC. The small signal stability models of both devices are then validated to ensure the accuracy of the derived models. STATCOM and UPFC power control mode are validated against PSCAD. The UPFC voltage control mode is validated against nonlinear solution of system equations.